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https://issues.apache.org/jira/browse/HBASE-2466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12859537#action_12859537
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ryan rawson commented on HBASE-2466:
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I think the API should be simpler, rather than providing 3 (!) ways to veto a
row, lets stick with 2.
The current Filter.java API is like so:
public boolean filterRow(List<KeyValue> kvs);
public boolean filterRow();
in the interests in compatibility, i would argue we should keep call #2 for
certain.
But the first call should be simplified to:
public void filterRow(List<KeyValue> kvs);
if an implementation wants to null out a row they do:
kvs.clear();
in their implementation.
That will make the RegionScanner implementation go from:
if (!returnResult && filter != null) {
// final chance to modify row contents
returnResult = filter.filterRow(results);
// final chance to drop the row... This may be superfluous with the
addition of the above?
// still needed for backwards compatibility however
if (returnResult || filter.filterRow()) {
results.clear();
}
}
to more like yay so:
if (!returnResult && filter != null) {
filter.filterRow(results);
if (filter.filterRow())
results.clear();
}
> Improving filter API to allow for modification of keyvalue list by filter
> -------------------------------------------------------------------------
>
> Key: HBASE-2466
> URL: https://issues.apache.org/jira/browse/HBASE-2466
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: filters, regionserver
> Reporter: Juhani Connolly
> Priority: Minor
> Attachments: HBASE-2466-2.patch, HBASE-2466.patch
>
>
> As it stands, the Filter interface allows filtering by
> Filter#filterAllRemaining() -> true indicates scan is over, false, keep going
> on.
> Filter#filterRowKey(byte[],int,int) -> true to drop this row, if false, we
> will also call
> Filter#filterKeyValue(KeyValue) -> true to drop this key/value
> Filter#filterRow() -> last chance to drop entire row based on the sequence of
> filterValue() calls. Eg: filter a row if it doesn't contain a specified
> column.
> It would be useful to allow for an additional API in the form of a step to
> prune the list of KeyValues to be sent by implementing an additional
> Filter#filterRow(List<KeyValue>)
> This would allow for a user to write a custom filter against the api that
> drops unnecessary KeyValues according to user-defined rules.
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